Is it the clutch plates wearing that requires adjustment every so often?

'14 Heritage Softail - Twin Cam 103. I adjust my clutch every oil change, 5,000miles. I like the 1/2 turn out adjustment.

Recently, nearing the end of my service interval I felt some slipping at high speed/loads - adjusted the clutch and back to normal.

Is clutch plate wear the reason that an adjustment is required once in a while? How will I tell when it's time to replace parts?

 

As it wears it will need adjustment, when it will no longer adjust it's time for plates.